Perhaps you should not worry so much with the month to month changes in
number of rows/columns.  Design a "worst case" scenario template and use it
each month.  Then instead of deleting unused rows/columns and messing up
formulas and results, HIDE them!  

Without knowing what kind of mistakes you're making, it's hard to make other
recommendations.  The use of named ranges (see Excel Help - search for the
phrase 'Define named cell references or ranges' for a beginning point) could
help you.  Don't use absolute references (=$A$15) unless you have to, use
relative addressing (=A15) so that when rows/columns are inserted/deleted,
the address updates in dependent formulas.

If bad goes to worse, set up a document that details the types of changes
you usually make and what you have to alter to keep the workbook working
properly.  Then read and follow your own instructions on making alterations
each month.